A deposition apparatus that deposits a thin film on a substrate in a vacuum chamber has been used in various industrial fields from long ago. In recent years, as represented by a semiconductor device and memory, stacking of a very thin film on the nanometer order is increasingly required. To meet such demand, among PVD (Physical Vapor Deposition) apparatuses that can deposit a very thin film of high purity, an apparatus that can form a stacked structure with high productivity and interface controllability by arranging two or more targets made of different materials in one chamber is frequently used.
FIG. 7 shows a sputtering apparatus including a plurality of targets as an example of a conventional technique. Such apparatus is disclosed in, for example, PTL 1.
Referring to FIG. 7, reference numeral 701 denotes a vacuum chamber configured to have an airtight structure, which is connected to an exhaust means (not shown) via an exhaust port 702 provided on the chamber wall, and is also connected to a sputtering gas instruction means 703.
A stage 706 is provided in the vacuum chamber 701, and configured to be able to fix an object 707 to be processed. Targets 704 and 705 made of a pure metal or metal compound are arranged in the vacuum chamber 701, and connected to a DC power supply (not shown) while being electrically insulated from the vacuum chamber 701. A switching means (not shown) is connected between the DC power supply and the targets 704 and 705, and can be used to select one of the targets 704 and 705 and supply power to it.
Furthermore, a shutter mechanism 708 including a rotation mechanism (not shown) is provided between the targets 704 and 705 and the object 707 to be processed. By causing the rotation mechanism to drive the shutter mechanism 708, it is possible to set one of the targets 704 and 705 in a shielded state and expose the other target to the object 707 to be processed.
A magnet (not shown) is provided in proximity to the atmosphere side of each of the targets 704 and 705, thereby enabling a magnetic field to be formed on a surface to be sputtered of each of the targets 704 and 705. When the object 707 to be processed is fixed to the stage 706, the DC power switching means is connected to the target 704 side, and the shutter mechanism 708 is driven to set the target 705 side in the shielded state, it is possible to form a film on the object 707 to be processed by particles sputtered from the target 704. When the switching means and the shutter mechanism 708 are respectively switched to the opposite sides to supply DC power to the target 705, it is possible to stack the film of the target 705 without extracting the object 7 to be processed from the chamber.
In the above-described technique, however, sputtered particles adhere from the sputtered target to the surface of the target that is not used for sputtering and its adjacent shield, and contamination occurs when the target is switched to perform deposition.
In the technique disclosed in PTL 1 described above, in the apparatus shown in FIG. 7, a gas introduction tube 710 and a valve 709 are provided near the target 704, and another gas introduction tube 711 and another valve 712 are provided near the target 705. In this arrangement, in addition to a gas introduced from the sputtering gas introduction means 703, a gas (to be referred to as a purge gas hereinafter) is introduced through the gas introduction tube and valve near the unused target to make the pressure in the vicinity of the unused target higher than that in the sputtering space, thereby making it possible to prevent contamination from the sputtered target.
In the technique described in PTL 1, however, by introducing a purge gas in addition to a sputtering gas, the purge gas reaches near the target used for sputtering, and it is thus impossible to make full use of the intended sputtering performance.
As a technique of reducing leakage of sputtered particles from the sputtered target to the outside, PTL 2 is disclosed (FIG. 8). In PTL 2, a rotating shutter 801 is configured to further drive in a straight line. Since the rotating shutter 801 can drive to also cover the side portions of a target 802 when shielding the target 802, thereby preventing sputtered particles from leaking from the target 802 to its periphery. Referring to FIG. 8, reference numeral 803 denotes an anode electrode; and 806, a ring-shaped cover capable of covering the anode electrodes 803.
It is, however, necessary to provide a power source such as a motor on the atmosphere side in the driving mechanism. Therefore, a complicated mechanism is required to simultaneously implement linear driving and rotation of the shutter mechanism in the vacuum chamber, thereby decreasing the reliability of the apparatus and increasing the cost.
Furthermore, as a sputtering apparatus that can prevent cross contamination by a double rotation shutter mechanism, PTL 3 is disclosed (FIG. 9). PTL 3 discloses a sputtering apparatus including a plurality of sputtering cathodes 942 provided in a vacuum container 911, a double rotation shutter mechanism, and a first deposition preventing shield 938. The double rotation shutter mechanism includes a first shutter plate 932 and a second shutter plate 934 that are individually, rotatably disposed. At least one opening 932a or 934a is formed in each of the first shutter plate 932 and the second shutter plate 934. The second shutter plate 934 is arranged at a position farther than that of the first shutter plate 932 from the sputtering cathode 942. The first deposition preventing shield 938 is disposed between the sputtering cathode 942 and the first shutter plate 932 to surround the side surfaces of the front region, on the first shutter plate 932 side, of the sputtering cathode 942.
In PTL 3, a cylindrical second deposition preventing shield 937 is provided between the second shutter plate 934 and the circumference of the first opening 932a formed on the first shutter plate 932 disposed on the side of a target 944, among the two shutter plates 932 and 934 constituting the double rotation shutter mechanism. The cylindrical first deposition preventing shield 938 is disposed between the sputtering cathode 942 and the first shutter plate 932 to surround the periphery of the front region of the target 944. This prevents sputtered materials from passing through the gap between the first shutter plate 932 and the second shutter plate 934 and that between the first shutter plate 932 and the sputtering cathode 942.
On the other hand, PTL 4 discloses a sputtering apparatus that can make an incidence angle small (FIG. 10). PTL 4 discloses a sputtering apparatus including a vacuum tank 411, a substrate arrangement portion 413 arranged in the vacuum tank 411, and a plurality of targets 4051 to 4059 arranged to face the substrate arrangement portion 413, wherein shield plates 421 to 423 in each of which a plurality of holes 431, 432, or 433 are formed are arranged at intervals between the substrate arrangement portion 413 and the plurality of targets 4051 to 4059. In PTL 4, sputtered particles obliquely emitted from the targets 4051 to 4053 adhere to the surfaces of the shield plates 421 to 423, and only vertically emitted particles can reach the surface of a substrate 412. Therefore, it is possible to uniformly form a thin film in micropores having a high aspect. When a sputtering gas is introduced from the vicinity of the targets 4051 to 4053, a reactive gas is introduced from the vicinity of the substrate 412, and the vacuum tank is evacuated from the vicinity of the substrate 412, no reactive gas enters the side of the targets 4051 to 4053, and thus it is possible to prevent the surfaces of the targets 4051 to 4053 from being altered.